Paper-pulp digester



UNITED STATES PATENT OFFICE;

HENRY 'W. STEBBINS, OF MONIOO, VISCONSIN.

PAPER-PU LP DI G ESTER.

SPECIFICATION forming part of Letters Patent No. 405,279, dated June 18, 1889.

Application filed April 21, 1888- fierial No. 271,394. (No model.)

To coZZ whom it may concern: I

Be it known that I, HENRY W. STEBBINs, of Monico, in the county of Forest and State of WVisconsin, have invented a new and useful Improvement in. Paper-Pulp Digesiers, of which the following is a full, clear, and exact description.

This invention relates to boilers or digesters for the reduction of wood or other fibrous materials to the condition of pulp, for making paper of different kinds or grades, by subjecting said material or materials to the action of sulphurous or other acids. These boilers or digesters are usually made of an iron or steel shell lined throughout with lead toprotect the shell from injury or destruction by the acid employed in the digester. Such leadlined boilers or digesters have been variously constructed, alike to provide for the unequal expansion and contraction of the two difierent metals employed in their construction and to support or retain the lead lining in place and intact.

My invention consists in a novel construction of such lead-lined boilers or digesters, substantially as hereinafter described, and pointed out in the claims, whereby I dispense with all hard-metal rings interposed between the sections of the body of the shell, flanges, and clamps operating to compress and thin the lead lining at the joints and to bulge out the lead beyond the joints in the body-sections, which causes the lead to crack and break, and whereby the lead lining is supported and retained in place with perfect freedom for the unequal expansion and contraction of the two metals, and the expense of operating the digester is largely reduced,

leakage is avoided, and the same bolts which unite the hard-metal sections of the body of the shell together and bring them up to the lead lining Within pockets formed' by said sections also serve to prevent the lead from leaving said pockets and .from bagging in case of Vacuum being formed within the di? gester.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar letters of reference indicate corresponding parts in all the figures.

Figure 1 represents a vertical section of a lead-lined boiler or digester embodying my invention; Fig. 2, a view in perspective of a portion of one of the shell-sections of the body; and Fig. 3, a vertical section of two of such adjacent shell-sections, in part, with lead lining in place before closing said sections on the lining.

A A indicate the outer iron or steel shell sections of the body portion of the digester arranged one above the other, and so as to form a close lap-joint, as at b, with each other. Each of these hard-m etal-shell sections is constructed at its upper end wit-h an inner annular bent offset 0, thereby, when the digester is set up, forming an annular pocket (Z between said shell-sections above where they lap, as at b, one against and over the other. These offsets c, which are integral with the sections A, may be formed in the sheets of iron or steel of which said sections are made during the operation of rolling or making the sheets; and said offsets may be of. any desired height to form the pockets d of therequired depthsay five inches more or less. Said pockets serve to receive portions e of the lead or soft-metal lining B within them free from being clamped or compressed by the'hardmetal-shell sections. 7

After the offsets 0 have been formed, as described, the same are split in direct-ion of and throughout their depth by cuts or incisions f, arranged at suitable distances apart-say so as to be at six inches apart, more or less, all around the shell-section. l-Ioles are made in these split offsets and in the outer walls of each shell A, to receive through them and through the pockets d screw-bolts g, having nuts on their outer ends and other holes made through the lap portions b of said shells for the insertion of rivets h. These several holes and the heads of the bolts and rivets fitting them are countersunk on the inside faces of said shells and in their offsets, so as to present a flush surface for the lead lining B over them.

The lead lining B is made up of a series of endless bands of suitable thickness and width and so as to extend all around theinterior of each iron or steel shell A, the same reaching from the bottom of one pocket d to the top of and over the next pocket above, at which point the lead or soft-metal sections are melted together by means of a blow-pipe or soldered.

The split oflsets c of the iron or steel shells A are suitably and snfiiciently bent inward toward the center of the boiler, as shown in Fig. 3, to easily admit of the lead lining B within them, after which said oifsets are drawn back onto the lead and toward the outer shell by the bolts g, which, however, are not so far tightened up as to bind the lead in the pockets (1, but to leave it free to independently expand and contract, and the two metalsthat is, the metals of the outer shells and liningto separately and unequally expand and contract; and here it should be observed that the effect is a very disastrous one to the lead when the latter is firmly secured to the steclor iron shell.

By properly adjusting the pockets d by the bolts 9 the lead lining B may be made free to work easily in expanding and contracting. The bolts g, however, not onlyserve to adjust the pockets, as required, but they also operate to prevent the lead from leaving the pockets in case of a vacuum being formed in the digestcr at the time of blowing off the contents of the digester,which usually causes the lead to bag. Said contents being blown out under pressure, it care is not taken, or from carelessness of the operator, a vacuum will be formed in the digester, and this has to be guarded against, so far as its effect on the lead lining is concerned, and is accomplished by the bolts g, which prevent the lead from leaving the pockets in addition to their other function of adjusting the pockets (Z by their action on the split oit'sets c.

The construction as described, too, prevents all thinning or stretching of the lead at the joints and bulging and cracking or breaking of it beyond the joints, and there is little or no necessity from time to time to tighten up the parts to prevent leakage.

The top section of the iron or steel shell and the next section below onto which it laps are secured together by means of bolts, as shown. This allows of the top section being easily removed to admit of the ready placing of the lead lining in position. The bottom iron or steel shell section may be secured to the next section above it by both bolts and rivets, as shown and as described, for the intermediate body-sections.

Man-heads C C are provided at top and bottom, also a steam-pipe z for supplying the di- 5 5 gester with steam, likewise a pipe 7c for charging it with acid or water, a pipe Z for blowing ofi' pressure, to which maybe added a steampressure gage; but all these and the method of applying the pipes form no part of this invention. 7

Having thus described my invention, what I claim as new, and desire to secure by Let ters Patent, is

1. I11 a digester, the combination of the overlapping hard-metal-shell sections constructed at their upper ends with inwardlybent annular offsets forming pockets above A their overlapping contact portions, and the soft-metal lining arranged to extend over and down within said pockets, substantially as specified.

2. In a digester, the hard-mctal-shcll sections AA, arranged to overlap one another, as at Z), and each constructed at their upper ends with inwardly-bent annularoftsets 0, split or divided in the direction of their depth, as at f, at suitable distances apart around each scction, and forming, in connection with the adjacent section, pockets (1, in combination with the soft-1netal lining B, arranged to extend over and down within said pockets, and the bolts arranged to pass through the pocket portions of the overlapping shcll-sections, essentially as and for the purposes herein set forth.

HENRY XV. STEB EINS.

\Vitnesses:

HENRY GRAEF, W. R. BURGESS. 

